Solid ink or phase change ink imaging devices, hereafter called solid ink printers, encompass various imaging devices, such as printers and multi-function devices. These printers offer many advantages over other types of image generating devices, such as laser and aqueous inkjet imaging devices. Solid ink or phase change ink printers conventionally receive ink in a solid form, either as pellets or as ink sticks. A color printer typically uses four colors of ink (yellow, cyan, magenta, and black).
The solid ink pellets or ink sticks, hereafter referred to as ink, sticks, or ink sticks, are delivered to a melting device, which is typically coupled to an ink loader, for melting of the solid ink into a liquid. A typical ink loader includes multiple feed channels, one for each color of ink used in the imaging device. In one type of solid ink printers, one common insertion port is provided for all the feed channels. In this type of solid ink printer an ink stick transporter transfers the ink sticks from a staging area to the appropriate feed channel. In another type, each channel has an insertion port in which ink sticks of a particular color are inserted through the insertion port. The ink sticks move either by gravity or urged by a conveyor or a spring-loaded pusher along to the feed channels. Each feed channel directs the solid ink within the channel towards a melting device located at the end of the channel. Each melting device receives solid ink from the feed channel to which the melting device is connected and heats the solid ink impinging on it to convert the solid ink into liquid ink that is delivered to a print head for jetting onto a recording medium or an intermediate transfer surface.
The insertion port or ports of a printer may be covered by a key plate having a keyed opening. The keyed opening helps to ensure a printer user places ink sticks of the correct variety into the insertion port. Each ink stick of a particular color corresponding to a feed channel has a particular shape. In the case of the common insertion port, the keyed opening is configured to accommodate all of the configurations for ink sticks intended for use in the printer. In the case of one insertion port for each feed channel, each insertion port may be keyed to allow only the ink sticks corresponding to the associated feed channel.
As the number of pages printed per minute increases for solid ink printers so does the demand for ink in the printer. To supply larger amounts of ink to printers, the cross-sectional area of the feed channels may be increased. Consequently, the insertion port for the channels and the keyed plate covering the insertion port are likewise enlarged. The larger opening enables smaller solid ink sticks to pass through without engaging the keyed plates over the insertion ports. Thus, solid ink sticks that do not conform to the appropriate colors for the feed channels can be loaded into the feed channel and delivered to the melting devices at the end of the feed channels. Even if a smaller stick has the correct color for the feed channel, its size may impair the ability of the stick to cooperate with guiding structure within the feed channel. Thus, excluding ink sticks that are not configured for use in a feed channel at the insertion port is a desirable goal.
Furthermore, situations arise in which the insertion of ink sticks into the insertion port is not optimal. For example, the insertion of several ink sticks of the same color into an insertion port may result in a back log of these sticks if the feed channel corresponding to the color of these ink sticks is already full. The issue of improper loading of ink sticks can be partially addressed by displaying messages on a printer screen. When the printer is powered down, however, the screen is blank and the printer cannot notify an operator that loading ink sticks corresponding to the filled feed channel would be improper.